SPD cleats are attached to cycling shoes and clip into SPD bike pedals.

They are used with the pedals to increase your efficiency and improve your power on climbing.

They release by twisting your heel out to the side. 

This type is typically used with indoor spin, gravel, MTB, and touring bikes, but can also be used with road or triathlon bikes. Compatible with 2-bolt or 5-bolt shoes. 

Two variations are available - the Wellgo 98a are equally compatible, but the Shimano SM-SH51 are longer lasting and of higher quality.